In their most widely-used forms, the rear doors of trucks and the doors of containers are composed of two panels. Each panel is kept in the position in which the door is closed through the cooperation of a shaft or casement bolt unitary with said panel and catch fingers unitary with the chassis of the truck or container. Said shaft, which is generally vertical, can turn around its longitudinal axis under the action of a control handle provided for this purpose; its lower end is bent at a right angle, and the resulting horizontal branch is designed to engage between the aforementioned catch fingers unitary with the lower part of the chassis. Said closure devices are not secure against break-ins, and they are generally locked using one or more padlocks, which, unfortunately, are easy to break.